Reliability of a processor may degrade over time. A counter may be implemented to track elapsed usage of the processor, which can be valuable in assessing continued reliability of the processor. Usage data is typically saved to storage, e.g., non-volatile memory that stores the usage data over the processor lifetime.
The processor may be powered down at any time, and the contents of the counter may be lost. If, for example, at each power down the counter value is lost, a drift in the counter value may result. For example, an average drift may be one-half of a “snapshot rate” (rate at which total usage is recorded) for every power down. In an extreme case, if the power down occurs more frequently than writes to memory, the counter will start over from zero after power up.